title: A single VHH-based toxin-neutralizing agent and an effector antibody protect mice against challenge with Shiga toxins 1 and 2.
abstract: Shiga toxin-producing Escherichia coli (STEC) is a major cause of severe food-borne disease worldwide, and two Shiga toxins, Stx1 and Stx2, are primarily responsible for the serious disease consequence, hemolytic-uremic syndrome (HUS). Here we report identification of a panel of heavy-chain-only antibody (Ab) V(H) (VHH) domains that neutralize Stx1 and/or Stx2 in cell-based assays. VHH heterodimer toxin-neutralizing agents containing two linked Stx1-neutralizing VHHs or two Stx2-neutralizing VHHs were generally much more potent at Stx neutralization than a pool of the two-component monomers tested in cell-based assays and in vivo mouse models. We recently reported that clearance of toxins can be promoted by coadministering a VHH-based toxin-neutralizing agent with an antitag monoclonal antibody (MAb), called the "effector Ab," that indirectly decorates each toxin molecule with four Ab molecules. Decoration occurs because the Ab binds to a common epitopic tag present at two sites on each of the two VHH heterodimer molecules that bind to each toxin molecule. Here we show that coadministration of effector Ab substantially improved the efficacy of Stx toxin-neutralizing agents to prevent death or kidney damage in mice following challenge with Stx1 or Stx2. A single toxin-neutralizing agent consisting of a double-tagged VHH heterotrimer--one Stx1-specific VHH, one Stx2-specific VHH, and one Stx1/Stx2 cross-specific VHH--was effective in preventing all symptoms of intoxication from Stx1 and Stx2 when coadministered with effector Ab. Overall, the availability of simple, defined, recombinant proteins that provide cost-effective protection against HUS opens up new therapeutic approaches to managing disease.
authors.affiliation: Department of Infectious Disease and Global Health, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts, USA.
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Tremblay
authors.forename: Jean
authors.initials: J
authors.lastname: Mukherjee
authors.forename: Clinton E
authors.initials: CE
authors.lastname: Leysath
authors.forename: Michelle
authors.initials: M
authors.lastname: Debatis
authors.forename: Kwasi
authors.initials: K
authors.lastname: Ofori
authors.forename: Karen
authors.initials: K
authors.lastname: Baldwin
authors.forename: Courtney
authors.initials: C
authors.lastname: Boucher
authors.forename: Rachel
authors.initials: R
authors.lastname: Peters
authors.forename: Gillian
authors.initials: G
authors.lastname: Beamer
authors.forename: Abhineet
authors.initials: A
authors.lastname: Sheoran
authors.forename: Daniela
authors.initials: D
authors.lastname: Bedenice
authors.forename: Saul
authors.initials: S
authors.lastname: Tzipori
authors.forename: Charles B
authors.initials: CB
authors.lastname: Shoemaker
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D054308:Enteropathogenic Escherichia coli / Q000276:immunology / Q000378:metabolism; D004927:Escherichia coli Infections / Q000276:immunology*; D005260:Female; D006463:Hemolytic-Uremic Syndrome / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D022622:Shiga Toxin 1 / Q000276:immunology* / Q000378:metabolism; D022641:Shiga Toxin 2 / Q000276:immunology* / Q000378:metabolism; D054323:Shiga-Toxigenic Escherichia coli / Q000276:immunology / Q000378:metabolism; D061905:Single-Domain Antibodies / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D022622:Shiga Toxin 1; D022641:Shiga Toxin 2; D061905:Single-Domain Antibodies